This invention relates to images captured by an array of pixel sensors and more specifically relates to the correction of visual artifacts in images of a moving scene to improve image clarity.
Imaging systems are used in a wide range of military and civilian applications. Central to many modern imaging systems is a focal-plane array (FPA), which consists of an array of detectors positioned at the focal plane of a projected image. The focal plane of an optical system is a point/plane at which the image is focused. Thus, in an FPA system, an array of detectors is located at a point where the image is focused. An X-by-Y array of sensors may be used to capture one frame of an image when a shutter is opened. Alternatively, a rotating mirror may sweep an image frame across one or more columns of sensors that store multiple time-based samples that collectively form one frame of the image.
The performance of FPA systems is adversely affected by the non-uniformity in the output response of each of the detectors in the array, also known as fixed-pattern noise. This may be especially observed in imaging systems that capture far away scenes. Some of the sensor parameters responsible for this issue may be identified in advance and minimized by a fixed camera-based compensation for each sensor. However, it has not been possible to compensate for all the parameters and changing environmental effects giving rise to fixed pattern noise. Some fixed pattern noise, a form of non-uniformity of output, results in an image with a superimposed pattern, e.g. striping, that varies due to difficult to predict environmentally changing parameters. A typical camera physically inserts a uniform target to obtain empirical data that is saved and used to remove a fixed noise pattern. Hence, improvement in the correction of fixed pattern noise is desirable in order to produce images with increased clarity.